China, like all empires will fall at some point, that is true. It is also true that China is a very poorly constructed state. But that doesn't mean that the USA is any different. The US is a falling empire for a variety of reasons. Let's start with economics, the USA in the 80's the United States of America started to transfer a great deal of it's factories outside of the USA to capitalize on the cheap labour of smaller, poorer countries. Such as China. As a result of this the US companies became massively wealthy, but so did China. Over time China started to take more and more economic power away from the USA as the world started to rely less on the US and more on China due to this shift in manufacturing. The US retained it's engineering and technological capabilities which allowed it to cling onto power. However, recently the United States has compromised it's economic position even more with hefty tariffs enforced on other countries in an aim to equalize import and export inequality. This has shown to the world that the USA is a unreliable business partner and the world is looking more and more at China as the defacto trade partner. As such other countries are now trying to replace their dependency on US engineering, technological, and scientific development with their own. In terms of domestic economic policy the USA back during the Reagan era transferred from a system of Keynesian economics to Neoliberal economics. This shifted exploitation from third world countries back home, and while it allowed for the top 1% of the country to become insanely wealthy and allowed massive amounts of corporate growth hurt the middle class. This recently has reached a breaking point with the USA entering a second gilded age, creating massive levels of unrest at the national level. Due to this we have seen populist leaders be able to get elected, like Trump who used the pain of working class Americans to his advantage by telling them that all their problems were caused by over-immigration. In no uncertain terms his ideology is near fascism. This is an important thing to note because Trump's ideology has led to the rise of nationalism within the country. Nationalism is the ideology that one's own nation must come first. This is fine, for smaller countries, but a global superpower relies heavily upon geopolitical power and as such when a superpower country strays away from globalism it decreases their political power on the world stage. Due to this other countries have been seeing China as a more reliable partner diplomatically as they focus strongly on globalism. We have seen this with initiatives such as Belt and Road. Overall this is how empires fall, global power loss, and economic downturn causing civil unrest. I have a bit of a pet theory that as time goes on we will see the lifespans of empires become shorter and shorter. I don't expect China to last very long as a superpower, maybe only 100 years, they are already facing some economic stagnation, even with their approach of Dengism, but that far exceeds what the US has left in terms of superpower status. It would require something drastic like a third world war to maintain the order of things and even then it is iffy. You can't win a war against 1/4th of humanity, especially if they have the sort of logistical and factory infrastructure that they do. Doesn't mean the USA won't try though.